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  <title>Document</title>
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<body>
  
  <script>
       Array.prototype.myMap = function(fn){
            let arr = []
            for (let i = 0; i<this.length; i++){
                 arr.push(fn(this[i]))
            }
            return arr
       }

      const arr =[1,2,3,4]
        const res=arr.myMap(item => `${item}ooooo`)
         

          Array.prototype.myFilter = function(fn){
               let arr =[]
             for(let i =0; i<this.length; i++) {
              fn(this[i])? arr.push(this[i]):''
             }
             return arr
          }

       const res1= arr.myFilter(item => item >2)
       console.log(res1);
  </script>
</body>
</html>